We now know what happened to an American grad student who disappeared in Iran months ago. An Iranian news outlet is saying that he is still in Iran and has been sentenced to 10 years in prison. It looks like his supporters were trying to keep his case quiet, hoping for a resolution. But now the Iranian authorities are speaking out. Princeton University says Xiyue Wang was doing research for his Ph.D. in Iran. He was picked up by the authorities, accused of spying. The claim is that he obtained highly confidential articles - whatever that means - for Princeton and other entities. The U.S. State Department says these charges are totally fabricated.

NPR's Peter Kenyon is following the story from Istanbul. And, Peter, what do we know here?

PETER KENYON, BYLINE: Well, we know that a spokesman for Iran's judiciary told the Mizan News Agency in Iran that Wang, quote, unquote, "infiltrated Iran on behalf of American and British institutions." Now, Iran is saying Wang wanted access to thousands of documents in the Iranian archives. It suggests he was engaged in espionage under cover of doing research. A hard-line news agency called Tasnim refers to Wang as the American spy. So...

GREENE: Oh, they've given him a title. My goodness.

KENYON: It's pretty clear what direction this is heading. Yeah. Princeton, for its part, says it's quite distressed by all this. The school says in the statement he was a fourth-year doctoral candidate. He was in Iran to research an old dynasty, the Qajar Dynasty - it's for his doctorate. They ruled from, like, the 1780s to the 1920s. So it's kind of hard to see why that would be a security threat to the Islamic republic. The State Department is not saying much. They usually don't in these cases. They're aware of the situation and continuing to work for the release of all Americans held in Iran.

GREENE: Well, if you are an American traveling to Iran, I mean, this is, like, the great fear, I mean, as outlandish as it might seem, that you'd be picked up and imprisoned. How often does this kind of thing happen?

KENYON: Well it happens. And there's been a flurry of cases, mostly involving Iranian-Americans. Tehran, of course, doesn't recognize dual citizenship. In the past few years, there's been the Namazis, businessmen Siamak Namazi, his father Baquer, who's in his 80s. They're still being held. Jason Rezaian, The Washington Post correspondent, was arrested with his wife. He was charged with espionage, finally got out in a prisoner exchange. And if you look a little farther back, there was a case that didn't involve Iranian-Americans, those three American hikers who were detained on the Iranian border in 2009.

GREENE: Right.

KENYON: That took more than two years before they were released.

GREENE: There was another arrest, a pretty high-profile one, an arrest of the brother of Iran's president, Hassan Rouhani. Is that somehow linked to all this?

KENYON: No, not linked. But it is important in its own way. Rouhani's younger brother, a man named Hossein Fereydoun, has long been the victim of allegations or been the target of allegations of corruption by hard-liners. It's a bit vague what exactly he's supposed to have done. But his connection to the president is obviously very clear and very important here. Hard-liners who did very poorly in the last election are out for a bit of revenge - is what Iranians are saying. And they're looking to make his second term as uncomfortable as possible. And because hard-liners still control large parts of the government, there are things they can do.

GREENE: OK. NPR's Peter Kenyon following these developments for us in Iran. Peter, thanks a lot.